Method of an apparatus for testing wiring

ABSTRACT

A test system employing a plurality of disconnect devices is provided. Each load, such as a lamp, has a local disconnect device which temporarily disconnects the load in order to protect it from high voltage during the test.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to International Application NumberPCT/GB01/05478 filed Dec. 11, 2001, which claims the benefit of priorityto Application Number 0030390.9 filed Dec. 13, 2000, in the UnitedKingdom.

BACKGROUND OF THE INVENTION

The present invention relates generally to the field of electricalwirings, and more specifically to a method of, and an apparatus fortesting the safety of the electrical wiring within buildings.

United Kingdom wiring regulations in accordance with British StandardBS7679 requires that the electrical wiring within buildings must beregularly checked to determine whether or not the wiring meets certainminimum standards of safety. However, the period of time between whichtests of the electrical wiring in a building must be carried out, are,in the majority of cases, not prescribed, except in respect of licensedpremises and buildings which are open to members of the public. Therequirements are often backed by the force of legislation, such as theElectricity at Work Act, the Health and Safety at Work Act and theHealth and Safety Regulations in the United Kingdom.

Generally, good practice with regard to the period of time between whichsafety tests of the electrical wiring in buildings is carried out, isaccepted as being between 7 and 8 years for domestic dwellings and 5years for offices and commercial premises. However, those buildings orpremises which are required to have a fire certificate must be testedannually. This includes licensed premises, hotels and buildings whichare frequented by members of the public.

As one would expect, any failure to carry out regular tests of thesafety of the electrical wiring in a building could lead to increaserisk from of dangerous or unsafe electrical installations. Furthermore,any accidents, injuries or deaths that occur as a result of dangerous orfaulty electrical installation, which has not undergone regular safetytests, may lead to the prosecution of those responsible. Prosecutionresulting from a failure to carry out the prescribed safety tests couldresult in substantial fines, imprisonment or both in extreme cases.

Therefore, the regular testing of electrical wiring in buildings isimportant not only to maintain and ensure the safety of those personsfrequenting such buildings, but it is also important in verifying thatthe subsequent installation or replacement of electrical components hasbeen carried out properly, thereby helping to avoid or mitigate againstthe installation of dangerous or faulty electrical components which maylead to failure of the wiring at a later date.

Part of testing of the safety of electrical wiring involves proving ordetermining the integrity of the insulation of all the electricalconductors (i.e.—live, neutral and earth). British Standard BS7679requires that the testing of the integrity of wiring insulation becarried out at a raised voltage of 1000 volts, in order to expose anypotential weakness in any component of the electrical wiring insulation.

However, great difficulty is often encountered when such insulationintegrity tests are conducted, especially on lighting circuits, due tothe fact that modern light fittings are sensitive and are thereforeoften incapable of withstanding the increased voltage associated withthe 1000 volt test prescribed in accordance with British StandardBS7679.

A further problem associated with carrying out the 1000 volt integritytest on lighting circuits, is that electronic circuits of modernfluorescent lights, discharge fittings and various other lightingcomponents generate electrical leakage which may lead to false testreadings, providing unsatisfactory test conditions and uncertain testresults. As a result of these problems, it has been necessary for anelectrician testing the lighting circuit to disconnect all of the lightfittings in a circuit in order to carry out the test properly. This is avery laborious, time consuming and expensive task. Once the electricianhas carried out the test he must then reconnect the lights and provethat they are all functioning correctly and safely after the test hasbeen conducted. In many instances the testing of electrical circuits ismade almost impossible due to the inaccessibility of lights as a resultof mounting locations or access restrictions.

Furthermore, due to the fact that the testing of electrical wiringcomprising lighting circuits is so labour intensive, time consuming andexpensive, in many instances testing of electrical wiring is often notcarried out properly or is not attempted at all, simply being ignored,having serious ramifications in terms of the integrity and safety of thewiring, and the associated safety of those persons frequenting suchbuildings.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided atest system comprising a test module and a plurality of disconnectdevices, each disconnect device being arranged to selectively disconnectat least one electrical load from wires supplying electricity to the atleast one electrical load in response to a first disconnect signal inorder that the integrity of the wires can be tested, each disconnectdevice being further arranged to reconnect the at least one load inresponse to a second signal, and said test module being arranged tocheck that all disconnect devices have disconnected before commencing atest.

One or more disconnect signal may be generated by the test module. Thetest module may be portable or may be provided as part of a buildingmanagement system.

Preferably the disconnect devices are responsive to a disconnect signalsupplied via a control line. The control line may run back to a controlboard.

As a further alternative, one or more control signals may be transmittedalong the supply cables (wires under test) themselves. This makesretrofitting into existing buildings easier.

Many modern light fittings include controllers that support anaddressable lighting interface. This interface may be used to controlisolation devices, such as relays, in order to disconnect selectedlamps. This interface may also be used to disconnect the lamp ballastsuch that the test can be performed.

The disconnect devices also enable the user to verify that the load aredisconnected before he commences a test. Thus each disconnect deviceincludes a signalling device that operates once the associated load hasbeen disconnected. Each disconnect device may report independently thatit has operated, the reports are ANDed or daisy chained such that eachdevice within the plurality of devices that are grouped together mustdisconnect its load before an indication is given that all the loads aredisconnected. However, in digital systems, the controller/test modulemay poll the disconnect devices to confirm that they have operated todisconnect the local load.

Advantageously each disconnect device may also give a local indicationthat it has disconnected its load. The indication may be visual oraudible. Use of an LED is a preferred way of giving a local indicationthat the disconnection has occurred.

A further test for disconnection can be performed by supplying mainspower along the cables that lead to the devices under test after thedisconnect signal has been given. Any devices that are still operatingclearly indicate that they have not disconnected. This can be monitoredremotely by measurement of the load on the circuit. If the current beingdrawn exceeds a threshold whose value is substantially that of thesmallest (least power consuming) device on the circuit, then it can beinferred that at least one device has not disconnected correctly.

Additionally or alternatively the device may respond to a signaltransmitted via radio (including bluetooth-RTM), infrared or ultrasoundto cause a disconnect to occur. Instructions to disconnect may also betransmitted over the wires under test. The reconnect can then occurafter a predetermined period of time or after the transmission of areconnect signal. In such circumstances a control circuit may monitorthe wires for signals. However a reconnect signal may, in somecircumstances merely be the absence of a disconnect signal.

The disconnect devices may be battery powered and/or may derive theirpower from the mains supply or from a remote DC supply, which may bederived from the mains or may be a battery. Short term storage may beprovided to operate the disconnect devices during the disconnect test.

Preferably the disconnect device includes at least one relay fordisconnecting the load. The load may comprise one or more lights.

In a preferred embodiment, each disconnect device may be remotelycontrolled by a control module, comprising a battery and/or chargingmeans, and a switch which when closed supplies a disconnect signalcausing the disconnect device to be activated. The control module alsocomprises a means for verifying that all the disconnect devices haveactivated. Said verification means may comprise an LED which when litindicates that all the disconnect devices have been activated and thatall the loads have been disconnected prior to carrying out testing ofthe wires. A fail safe function is therefore included such that a testcannot be performed until all the disconnect devices have operated.

According to a second aspect of the present invention there is provideda method of testing lights connected to a power supply via a test systemaccording to the first aspect of the present invention, the testcomprising the steps of asserting a disconnect signal to disconnect thelights, confirming that all the lights have disconnected, performing atleast a test of the insulation or continuity, supplying power to thelights and reconnecting the lights.

Those skilled in the art will further appreciate the above-mentionedadvantages and superior features of the invention, together with otherimportant aspects thereof upon reading the detailed description thatfollows in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For more complete understanding of the features and advantages of thepresent invention, reference is now made to the detailed description ofthe invention along with the accompanying FIGURES, wherein:

FIG. 1 schematically depicts the configuration of a test circuit inwhich signals to the disconnect device are provided along the wiresunder test;

FIG. 2 schematically depicts an arrangement in which the signals to thedisconnect device are provided along dedicated control wires;

FIG. 3 schematically depicts a test arrangement according to anembodiment of the present invention in which signals to the disconnectdevice are provided along control signal wires which may be provided aspart of an addressable lighting control system; and

FIG. 4 depicts an arrangement similar to that shown in FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

Although making and using various embodiments of the present inventionare discussed in detail below, it should be appreciated that the presentinvention provides many inventive concepts that may be embodied in awide variety of contexts. The specific aspects and embodiments discussedherein are merely illustrative of ways to make and use the invention,and do not limit the scope of the invention.

FIG. 1 depicts the supply arrangement for a fluorescent lamp, generallyindicated 2. The lamp receives a mains electricity supply from thebuilding supply rails (not shown) that, in turn, are connected to thesupply input of a circuit breaker 4. The “live”, “neutral” and “earth”supplies are then output from the circuit breaker 4 and are connected toa high frequency ballast unit 6 of the lamp 2. Interposed between thecircuit breaker 4 and the ballast unit 6 is a disconnect device 8. Thedisconnect device 8 includes switching means, such as relays, operableto disconnect the live and neutral supplies to the ballast 6.Optionally, they may also be operable to disconnect the earthconnection. In the arrangement shown, the disconnect unit 8 receives acontrol signal which is carried on the neutral and earth conductors ofthe circuit under test. Use of the neutral and earth conductors areadvantageous since both of these should be at approximately 0 volts inuse. However, it is also possible to encode the control data on the liveconductor if necessary.

A control test panel 10 is provided which has a test connection to thecircuit breaker 4. This allows the control test panel 10 to generate thedisconnect signal and to superimpose it onto the appropriate ones of theconductors under test in order that the signal can be supplied to thedisconnect device 8.

Multiple disconnect devices having associated lamps may be run inparallel off the main supply. When this is done, it may be desirable toadd a daisy chained test line running from device to device such that asignal can be generated confirming that each and every device hasoperated to disconnect its associated lamp.

In use, the control test panel sends a signal to the disconnect device 8in order to cause it to disconnect the lamp and ballast 2 and 6respectively, from the mains supply. Optionally the control test panelmay also send a signal to the circuit breaker in order to cause it todisconnect its circuit from the mains supply. The conductors, generallyindicated 14, can then be subjected to the high voltage insulation testin order to confirm their reliability.

FIG. 2 shows an arrangement similar to that shown in FIG. 1, except nowthe control signals to the disconnect device 8 are provided alongdedicated control lines 16. This removes the necessity to superimposethe disconnect and reconnect signals onto the wires under test. This hasthe advantage in that the control circuitry for the disconnect devicedoes not have to be designed to withstand the high test voltages whichare used.

FIG. 3 shows an embodiment of the present invention that comprises anarrangement similar to that shown in FIG. 2, except that the disconnectdevice 8 is now connected to a control signal bus 16′ which itself isinterfaced to a building management system 18 which may receive an inputfrom the control panel 10 or which may have the control panel 10integrated therein. The bus 16′ may be a data bus of a recognisedstandard, such as the digital addressable lighting interface (DALI) orEuropean information bus (EIB) protocols. Thus individual disconnectdevices 8 may be addressed on the bus to selectively connect anddisconnect. Thus, not only can the building management system 18instruct the devices to disconnect, but providing the disconnect devices8 also support bi-directional communication it may then poll eachindividual device to confirm that the disconnect has indeed occurred.The test may then be performed only when all of the devices confirm thatthey have successfully disconnected.

FIG. 4 illustrates an arrangement similar to that shown in FIG. 3, butwherein each ballast unit 6 has a DALI interface 20 associated therewithsuch that the lamp brightness can be controlled by suitable control ofthe high frequency ballast. A multisensor 22 and a switch 24 areprovided such that the control test panel 10 can be selectivelyconnected to the DALI bus 16′ and such that the results from the testscan be picked off from the bus and routed to a data acquisition unit.

It is thus possible to provide a lighting test system.

In a modification of the invention, wireless communication may beprovided between the control unit or each disconnect device. Thus eachdisconnect device would require at least a local receiver and optionallya local transmitter in order that it can signal to the control devicethat it has disconnected its load. Constructional details oftransmitters and receivers are within the scope the person skilled inthe art and need not be described here in detail. It is expected thatsuch transmitters could be bluetooth (RTM) devices.

Each disconnect device 8 may remain permanently disconnected until suchtime as it receives a reconnect signal, or alternatively it may bearranged to reconnect after a predetermined time as lapsed. The mode ofoperation may be freely selected by the user.

Additional objects, advantages and novel features of the invention asset forth in the description that follows, will be apparent to oneskilled in the art after reading the foregoing detailed description ormay be learned by practice of the invention. The objects and advantagesof the invention may be realized and attained by means of theinstruments and combinations particularly pointed out herein.

1. A test system comprising: a plurality of disconnect devices and atest module arranged to be in communication with each of the pluralityof disconnect devices, wherein each disconnect device is arranged toselectively remove at least one electrical load from connection betweensupply wires supplying electricity to the at least one electrical loadin response to a first disconnect signal provided by the test module inorder that the integrity of the wires can be tested, each disconnectdevice being further arranged to reconnect the at least one load inresponse to a second signal, and wherein the test module is arranged tocheck that all of the loads have been removed from connection betweenthe supply wires before commencing a test.
 2. The test system of claim1, wherein the second signal is generated by the test module.
 3. Thetest system of claim 2, wherein the test module is portable.
 4. The testsystem of claim 2, wherein the test module is part of a buildingmanagement system.
 5. The test system of claim 1, wherein eachdisconnect device is responsive to a disconnect signal supplied via acontrol line.
 6. The test system of claim 1, wherein each disconnectdevice is responsive to a control signal transmitted along the wiresunder test.
 7. The test system of claim 1, wherein each disconnectdevice includes a local signaling device that operates once the load hasbeen disconnected.
 8. The test system of claim 7, wherein the loadsignaling device is an LED.
 9. The test system of claim 1, wherein eachdisconnect device can be polled in order to determine its status. 10.The test system of claim 1, wherein each disconnect device is arrangedto reconnect the load after a predetermined period of time.
 11. The testsystem of claim 1, wherein each disconnect device is arranged toreconnect the load upon receipt of a reconnect signal.
 12. The testsystem of claim 1, wherein each disconnect device is arranged toreconnect the load in response to the absence of the disconnect signal.13. The test system of claim 1, wherein each disconnect device ispowered, wherein the power is selected from the group consisting of abattery, a main supply, a remote DC supply, and combinations thereof.14. The test system of claim 1, wherein communication between the testmodule and the disconnect devices is via wireless transmission.
 15. Thetest system of claim 1, wherein said electrical load comprises alighting device.
 16. A method of testing wiring to lights connected to apower supply via a test system comprising a plurality of disconnectdevices and a test module arranged to be in communication with each ofthe plurality of disconnect devices, each disconnect device beingarranged to selectively remove at least one electrical load fromconnection between supply wires supplying electricity to the at leastone electrical load in response to a first disconnect signal provided bythe test module in order that the integrity of the wires can be tested,each disconnect device being further arranged to reconnect the at leastone load in response to a second signal, wherein said test module isarranged to check that all of the loads have been removed fromconnection between the supply before commencing a test, the testcomprising: asserting a disconnect instruction to disconnect the lights;confirming that all lights have disconnected; performing at least a testof continuity; and reconnecting the lights.
 17. A method of testingwiring to lights connected to a power supply via a test systemcomprising a plurality of disconnect devices and a test module arrangedto be in communication with each of the plurality of disconnect devices,each disconnect device being arranged to selectively remove at least oneelectrical load from connection between power supply wires supplyingelectricity to the at least one electrical load in response to a firstdisconnect signal provided by the test module in order that theintegrity of the wires can be tested, each disconnect device beingfurther arranged to reconnect the at least one load in response to asecond signal, wherein said test module is arranged to check that all ofthe loads have been removed from connection between the supply wiresbefore commencing a test, the test comprising: asserting a disconnectinstruction to disconnect the lights; confirming that all lights havedisconnected; performing at least a test of insulation; and reconnectingthe lights.